structured_data filter throws Liquid error when first media isn't an image

[bertiful]

The structured_data filter throws a Liquid error: invalid url input error when a product has the following conditions:

1. A single variant
2. The first media isn't an image, i.e. a video or 3D model

Usage:

<script type="application/ld+json">
  {{ product | structured_data }}
</script>

There may be other product setup conditions that affect this. This happens in Dawn as well.

cc @ludoboludo @tyleralsbury (👋🏻)

[tyleralsbury]

Thanks for this, @bertiful . I'll bring it to the team and we'll see what we can do.